This invention relates to non-woven fiber batts. More specifically, this invention relates to a process of forming a non-woven fiber batt into a pad having a convoluted surface.
In futons, mattresses and upholstery cushions, different types of filling materials are used to create a range of comfort and height characteristics. There are a number of advantages to be achieved by construction of batts from synthetic, staple fiber material for use in mattresses and upholstery. Such fibers are inherently lightweight and therefore easy to ship, store and manipulate during fabrication. These fibers are also generally less moisture absorbent than natural fibers such as cotton, or cellulosic based synthetic fibers such as rayon. Therefore, products made from these fibers can be maintained in a more hygienic condition and dried with much less expenditure of energy. When subjected to open flame, many of these fibers also tend to melt and drip rather than burn. While some of these fibers give off toxic fumes, the escape of such fumes has been avoided or minimized by encapsulating the batt in a fire retardant or relatively air impermeable casing. In contrast, fibers such as cotton burn rapidly at high heat and generate dense smoke.
Futon furniture in recent years has become a popular alternative to standard upholstered furniture. Futon couches, loveseats and chairs can be repositioned so that the furniture can be used as a bed. Futon beds that do not convert into seats or couches are also commercially available. Traditionally, polyurethane foam has been combined with other types of cushioning materials such as cotton batting, latex rubber, and various man-made fiber products in order to impart the desired comfort characteristics to a final product. With time and use, the various types and combinations of materials take on different degrees of set as a result of compression from the weight of a human body. As is often the case with the softer materials, the final product will take more set over time with continued use. The more set the product takes over time, the more comfort, flexibility and height is lost from the product. Especially with futons, it is desirable to bend, fold and/or roll up a futon mattress to be used as a sofa or for storage when the futon is not used as a flat sleep surface. Yet, when the futon is used as a sleep surface it must be stiff enough to span slats in a bed frame. Preferably, the material used in making the futon would take on little or no set.
Synthetic fiber batts have been used in these products instead of or in addition to polyurethane foam since batts maintain their comfort characteristics over time. However, traditional batts with the desired comfort and height characteristics are generally too stiff to allow a mattress or futon to be easily rolled for storage or folded into a couch. One such batt is shown in U.S. Pat. No. 4,668,562. This batt would be undesirable for use in a futon mattress since in order to create a mattress with desired comfort characteristics a very thick uniform batt would be needed resulting in a product which would be difficult to fold or bend in order to store the mattress.
It is therefore an objective of the present invention to provide a non-woven fiber pad having improved compression and loft maintenance in order to resist permanent set over time.
It is also an objective of the present invention to provide a non-woven fiber pad that has improved compression and loft characteristics while remaining stiff enough for traditional applications.
It is further an objective of the present invention to provide a process for forming a non-woven fiber pad.
The objectives of the present invention are achieved by forming a non-woven fiber pad with a convoluted surface and an integral relatively thin but stiff base from a non-woven fiber batt made of polyester fibers. The batt is introduced between a pair of counter-rotating drums, at least one of which has a convoluted surface. As the fiber batt is drawn between the counter-rotating drums, the convolutions upon the surface of at least one roller compresses the surface of the non-woven batt in frictional engagement therewith to a greater or lesser degree depending on the degree of surface relief of the roller convolutions.
A heated wire is placed generally parallel to and between the pair of drums so that as the non-woven batt is drawn between the drums and is compressed by the drum convolutions, the heated wire cuts through the non-woven batt creating a cut-pattern generally mirroring the convolutions on the surface of the drum compressing the non-woven batt. That is, where a drum convolution compresses the batt in the vicinity of the heated wire, the wire passes through the batt at a point nearer to the batt surface which is in contact with the drum convolution. Because the cutting wire is heated, the fiber in the non-woven batt melts at the surface during the cutting operation and bonds to adjacent fibers as the melted surface cools, creating a skin that retains the convoluted pattern.